Protective apparatus for alternating-current elevators.



NG CURRENT ELEVATORS.

APPLICATION FILED JUNE 9, l906. RENEWED JUNE 10, 1909.

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- APPLICATION FILED JUNE 9, 1906. RENEWED JUNE 10, 1909. 950,224:w

Patented. Feb. 22, 1910.

4 SHEETSSHEET 2.

Qwi/tmeooao I Walw C (7' M @MZZ W. N.'DIGKINSON, h. PROTECTIVE APPARATUS FOR ALTERNATING CURRENT ELEVATORS.

APPLICATION P ILED JUNE 9, 1906. RENEWED JUNE 10, 1909. 950,224. Patented Feb. 22, 1910.

4 SHEETS-SHEET 3.

ME 2 a" Q/vi/bmeooeo W. N. DICKINSON, JE- PROTEGTIVE APPARATUS FOR ALTERNATING GURRENT ELEVATORS.

APPLICATION FILED JUNBQ, 1906. RENEWED JUNE 10 1909.

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' UNITED s'rATns PATENT orrrcn.

WILLIAM H. DICKINSON, 38., OF NEW YORK, CITY, NEW JERSEY,

5 cour'am', or JERSEY "rno'rnc'rrvn arrm'rns non A pplicatton filed June ,9,

To all whom it may concern;

Be it known that I, WILLIAM N. Drciun- SON, Jr., a citizen of the United States, residing in New York city, borough of Brooklyn, and State of New York, have invented a new and useful Improvement in Protective Apparatus for Alternating-Current Elevawhich the following is a specification.

My invention relates to ap aratus for controlling electric motors, an although it is herein shown applied to a hoist of an elevator system, itmay have a general application.

The primary object of my invention is the provision of brake apparatus for an electric motor and means for automatically etfecting the application of the brake upon the main line current being interrupted.

A further-object .of'the present invention is the provision of a torque release brake for electric motors dependent directly upon the motor itself for its operation.

Another object of my invention is the pro- VlSlOIl of means for operatin a brake to release position and holding it insuch POSI- tion, with minimum consumption of current.

A further object is the provision of a torque release brake in combination with economic and safe means for controllin alternating current motors of the single p 1358 apparatus from or multiphase type.

The movement within limits of one of the members of the power motor mounted as described in this specification, also provides a convenient means for protecting the whole undesired results due to unexpected change in phase relation on a multiphase circuit. A device of this nature is described in my co-pendin application, Serial Number 321,692 filed une 14, 1906 for an improvement in safety devices for alternating current hoisting apparatus.

Other objects of my invention will appear hereinafter, the novel combination of elements being pointed out in the claims. Y

In the accompanying drawings, Figure 1 represents diagrammatically an elevator system with my invention applied thereto; Figs. 2 to 6 inclusive illustrate the brake apparatus and details thereof; Figs. 7 to 12 in- -lusive show-various centering devices that ma be used if desired; and Figs. 13 to 18 inc naive show the electric means for hold- Speemeation of Letters Patent. 1908,801181 80. 820,957. Renewed June 10, 1909. Serial No. 501,436.

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ALTEBNATING-CUBRENT ELEVATORS.

Patented Feb. 22, 1910.

ing the brake in released position, and modifications of such means.

It should be particularly noted that one of the limiting conditions of the size of elevator apparatuswhich may be installed to operate upon alternating current circuits, is the amount of startin current required by the elevator motor anthe brake releasing mag- This starting current being thrown upon the. line at irregular and possibly frequent intervals, will tend to disturb the otential of the-line to the detriment of lig ting or other power service, or even possibly so lower the potential of the line as to interfere with the efficient actionof the elevator apparatus. It becomes important, therefore, to reduce the amount of starting current required by the elevator, but at the same time to in no ,wise sacrifice the safety features of theelevator apparatus. Certain types of motor windings and startin devices to correspond therewith, are emp oyedin connection with alternating current motors for the purpose of obtaining great startin torque with small expenditure of current, ut the speed re ulation of themotor should also be conknown means of overcounter weighting an electric elevator in order to allow the use of a small power unit and to add to the total operating etliciency of the device, carriers with it the condition that at times'the tendency exists for the load to drive the hoisting drum rather than the hoisting apparatus to drive the load.

Should the hoisting drum be driven by the load and consequently, therefore, also the motor, it is desirable that. the latter should exert an elcctro-dymunic braking effect after the current is cut oil from the motor or is reduced. A means of producing a dynamic braking effect in the alternating current mo tor is treated of in my co-pcnding applies--- tion, SenalNo. 292,544, filed'Dec. 20, 190 for an improvement in electro dynamic brake for alternating current motors.

desired this latter means may be employed in conjunction with the device which ever, that with a mechanical control alternating current elevator, the operation of the control and the lifting of the brake when the supply of current is cut ofifrom the circu t,

. would introduce an element of danger in connection with any elevator machine which I am now describing. It will be evident, how-' is suiliciently eiiicient to allow the unbalanced lhad, either on the car side or on the counterweight side, to start the machine from rest. This is for the reason that in the event of the sition, it would be possible for the elevator, under certain load conditions, to attain a speed far in excess of its normal maximum owing to the fact that there is no inherent retarding action in the motor itself to prevent this. In a direct current elevator system, the connection of the armature to the field forms a convenient, and the usually employed means for covering this point. In an alternating current elevator equipped with an electric brake, this same danger is present only to a limited dc ee, as it will be evident that by the operation of the car control itwill be impossible to release the brake on the hoisting machine unless current is prescut on the lines. It will also be evident'that a broken or dis-arranged connection or connections of the tion for the brake would still allow of'the same runaway conditions obtaining. To secure the release of the electric brake requires expenditure of current at the time when it is desirable to cut down such current, that is, at the time of the starting of the elevator.

As an electric brake of the type now usually employed requires a very large current until its magnetic circuit has been closed, the employment of the ordinar type of electric brake brings up serious ObJGCtlOIl rom the operative standpoint. In both of the above remises not only is the maximum speed attained to he considered as the danger element, but the fact that with the brake released 'and no current bein supplied to the motor, the elevator car is liable to start in either direction, depending upon Whether the predominate weight exists on the car side or the counterweight side at the time, irrespective of whether the control which has released the brake has been thrown either for the up motion or for the down motion, presents thecontingency that the elevator machine may move 1n the direction opposite to that which it would move if the current supply to the motor were perfect. And in this event the' automatic stop devices hereto fore usually employed for bringing the elevator to rest at predetermined or terminal landings under normal conditions, would be either entirely useless or rendered materially ineffective, and the continued travel of the car and the counterweights beyond normal limits would result, either effect depending upon the speed and weight of the moving mass.

In consideration of the above, it will be obvious that the application of a braking device whose action must from its nature be co-incident with and dep nd upon the introduction and interruption of current into the brake being lifted to theoff p0 motor with a perfect connecen earpower motor, is to be desired. The device Which I am about to describe is based upon this principle.

' Referring to Fig. 2, it will be seen that the stator l of the alternating current motor M is mounted in bearings 52, 2, which may be of any desired type. These bearings are placed in convenient positions at the upper ends of the supports or standards 3, 3 secured to the bed plate B. The journals of the stator arc rigid with the stator frame and are designated by the reference numbers 4, L. The axis of the stator bearin s is co-incident with the axis of the rotor shaft 5, in that the journals 4, 4 themselves form bearings for the rotor shaft 5. It is therefore evldent that the stator may be given a. rotative movement about the rotor and the latter rotated within the stator. The stator frame 1 carries a downwardly extending arm orlug 6, in this instance, by means of which centralizing springs or other centralizing forces keep the stator, when little or no current is present in the motor, in an approximately definite position. Means may also be provided in connection with such arm or extension 6 for limiting the rotative movement in a direction concentric with the rotative movement of the rotor. Such means may comprise devices placed in fixed position in the path of'the arm or In 6, as for example the circuitclosers an holdin magnets illustrated in Figs. 13 to 18, inc usive. The limiting devices whether in the form of separate abutments or in the form of circuit-closers and holding-ma ets,'as ex lained, are preferably locate on the be plate, but may be placed wherever desired. For instance, they may be secured on the inner sides of the bed plate B, an openin for the passage for-the arm 6 being rovi ed in the top of the bed plate in an o vious manner.

In Fi 1, I have shown an ordinary multiphase induction motor of the squirrel cage type connected to an elevator winding machlne E, the whole being equipped with a brake 7 which is adapted to be applied to the brake pulley 8 on the rotor shaft 5. This pulley may be in the form of a coupling between the shaft of the motor and the worm shaft of the winding machine. The motor may have a definite wound rotor provided with slip rings connected to an exterior starting device. Or said motor could be of any of the well known single phase types, or it could be a double motor arranged either in a single casing or a double casing, for the purpose of reducing peripheral speed, and therefore the braking effort necessary, or for reducing the starting current, or for other reasons, without departing from the braking principles herein described. I have shown a simple motor merely for the sake of clearness.

.011 the exterior of the stator casing 1 is left-hand end as viewed in the figures, to

the brake which is illustrated indetail in Fig. 4. Obviously any suitable brake apparatus may be employed, but in this instance I have shown a toggle connection 14 between the lever and the lower ends of the brake I. By means of the spring and bolt 16,

- the brake is applied to the pulley 8 whenever the roller 11 lies in the recess 12 of the cam 9. lVhen, however, the cam 9 1s actuated so as to move the lever 10, the brake will be released againstthe action of the spring 15. In other words, the movement of the cam 91 in either direction from center will cause the roller 11 to ride on one of its higher points and thus release the brake. The return of the cam to its central position will allow the roller to again lie in the recess 12, being forced to such position by the brake spring 15. That is, the cam 9 maybe so shaped that it will not only actuate the lever 10 to release the brake, but will also permit the spring 15 to return the stator to normal or central position. Other centering devices as shown in Figs. .7 to 12 inclusive,

and hereinafter explained in detail, may

also be used if desired.

With no current in the motor, the stator is held in central position and the brake is applied. Upon the introduction of current to the motor, the rotor being held stationary by the brake, the torqueproduced between the stator and therotor will eifect the rotation of the stator either in one direction or the other, dependingv upon the phase relation of the current introduced. The stator being so rotated, carries with it the cam 9 which actuates the brake lever 10, and which in turn releases the brake. \Vhenthc stator is thus rotated andthe brake released, the arm 6, as indicated in Figs. 13 to 18 inclusive, moves with the stator. The armatures 18, 18 carried by said .arm are moved against the poles of the alternating current magnet 1 or 17', depending on the direction in which the stator l is moved. Insulated contacts carried by the arm 6 are also moved into engagement with certain fixed contacts.

Referring particularly to Fig. 13, it will be seen that the arm 6 is provided with an extension 19 of insulation, which extension carries the contact pieces 20, 21 and 22 which are respectively connected'to the stator terminals 26, 27 and 28 by means of the wires 29, 30 and 31. 'Assuming that the stator 1 is moved in a clockwise direction as viewed able retarding means in Fi 13, the movable contacts 20, 21 and 22 wil be moved into engagement with the fixed contacts 23, 24 and 25 respectively. Substantially at the same time, or a short time before, the armature 18 is brought into engagement with the holding magnet 17 so as to close its magnetic circuit before it. is

energized. \Vhen themovable contacts have been thus brought into engagement with the fixed contacts, a circuit is closed from the main line through the single phase electromagnet to which are connected the leads 32 and 33. Upon the energization of the electro-magn'et 35 the switch 36. will be closed and current will flow to the holding magnet 17 from the fixed contacts 23, 2+ and 25 through the wires 32. 33 and 3% respectively. The holding magnet is thus energized while its magnetic circuit is closed, and, therefore, this magnet takes only a very small current but firmly holds the stator in the osition to which it has been rotated by the initial torque. I

Fig. 14 illustrates a principle of inertia in which the inertia feature is in the movable contact-carrier, the contact being mounted on a light spring 38 but insulated therefrom and made heavy or provided with a weight 37. On the'sudden throwof the stator due to initial torque, the movable contacts 20, 21 and 22 will lag behind in move-' ment owing to the inertia of the spring 33 and the weight 37. This will allow the armature 18 or 18' to be brought into magnetic contact with the poles of the holding magnet 17 or 17 before the circuit of such magnet isclosed. That'is, the magnetic contactof the holding magnet will be made before the resilient strength of the spring overcomesthe inertia stored up in the suspended contacts or in the weight 37, but as soon as its inertia has been overcome, the spring exerts its closing force and brings the electrical contacts 23, 24 and 25 or 23, 24 and 25 into electrical circuitwith the solenoid of the holding magnet 17 or 17 Fig. 15 illustrates a spring 38 connected to the lower end of the arm 6 and obstructions 39 and 39 placed in the path of movement of the lower end of said spring. When the stator is rotated in one direction or the other, the lower end of the spring 38 will strike against one of these obstructions and then snap by the same. The closing ofthe electrical contacts will therefore be delayed until the magnetic circuit has been closed.

either directly or in conjunction with suitto form any requisite electromagnet magnet coils by the magnet 35,

"caused by the initial torque,

time element desired.- The initial torque throw of the stator elect-rifles the contacts of switch 36 or 36 controlled .by the electromagnet 35 or 35', and also com letes a circuit to the solenoid of either 0 said magnets sli htly before the magnetic circuit of the hol ing magnet is completed, in order to obtain a firm electrical contact by means of a slight further movement of the stator 1. That is, the contacts 20, 21 and 22 may be brought into electrical connection with the fixed contacts 23, 24 and 25 a short time before the armature 18 is broughtinto engagement with the poles of the holding magnet 17. Then assuming a slight flexibility ofthe parts, the arm 6 will be moved farther until the armature 18 meets, the poles of the magnet 17 and the movable contacts will therefore be brought into firmerengagement with the fixed contacts. The delay caused in closing the electric circuits to the holding prevents the com letion of the electrical circuit to the holding magnet coils until their circuit has been completed. The magnet 35 or 35 having but a small duty to perform, will require only a fraction of the current necessary for the holding magnet coils.

Fig. 16 illustrates a method in which the holding magnets 17 and 17 are mounted so as to be slightly movable preferably in the arc of a circle, and ma be arranged either with -a coil s ring as indicated at 40 and 40, back of the libldmg magnet, in a self-centering socket 41 or 41', or the ma et may be mounted on an arm hung radia ly from the same axis as the stator. On 'the impact the live contacts carried by the stator arm 6 will engage with the terminals 42, 43 and 44 connected with the holdin' magnet coils and mounted in any suitabF manner in a stationary'frame adjacent the holdingv magnet. The relative distance arrangement of magnetic contacts and electrical contacts is such that the former will be com leted first and the inertia stored up in t e stator will cause the holding magnet to be carried back against its flexible backing or spring 40 or 40 At this time the live contacts on the stator lug will be brou ht into electrical connection with the fixe terminals so that the holdin will then be energized to hold the stator within the limits of the movement of the magnet in its centering socket or hold ing frame. As the pole pieces of the ma r et 1? are .movable in the arrangement ill ii trated in Fig. 16, and the contacts 42, 43 and 44 are stationary, the inertia throw of the stator drives, the contacts carried by the stator arm 6 .in between the contact clips 45, 48 and 47, which are connected to the rods 48, 49 and 50 respectively. These rods are provided with heads 51,52 and 53 between connections between magnetic which and the fixed frames 42, 43 and 44, are placed the springs 54, 55 and 56. It will thereforebe seen that the rods 48, 49 and. 50 must slide through the'parts 42, 43 and 44 as bearings, and that the clips 45, 46 and 47 are normally held in outward position by the springs 54, 55 and 56.

If the torque conditions are such as to allow either the backing springs 40 or 40 in the holdin magnet frame to return the magnet to its former position, the electrical the contacts on the stator arm 6 and the clips 45, 46 and 47 will still be maintained as the latter have a strong friction hold on the former and are connected to the springs 54, 55 and 56 in such a manner that they may be moved to ward a short distance without coming against a solid stop which would allow the stator contacts to e dis-engaged from said clips. With this arran ement, not only will there be a firm electrica connection between the stator arm terminals and the switch contacts for the holding electro-magnet, but vibrations due to alternations of current in the stator or variations of main line voltage, will be absorbed by the spring 40 or 40.

17 illustrates a method whereby the electric circuits to the holding magnet coils are completed by means of contact between the armature and pole pieces of the ma et itself. A commercial type of multip iise magnet is here shown in which the magnet is'made up of two ma right angles to one anot etic circuits set at er, the iron cores of which are electrically insulated from each other, as are also the armatures for the pole pieces, said armatures being carried by the stator frame 1. '18 designates the armature structure which is shown rigidly'connected with-the stator frame 1 but insulated therefrom. Carried by the armature structure .18" but insulated therefrom, is an electrical contact 57 and in the path of movement of this contact are fixed contacts 58 and 58'. The connections to one end of each of the two ener izingcoils of the holding ma 'net are comp eted through the cores and t eir corresponding armatures, and the common return for the two holding magnet coils may be completed through the third contact 57. The movable contact 57 may be brought into. engagement with the fixed contact 58 or 58' before the magnetic circuit is closed, without interfering with the desired result in the device.

Fig. 18 illustrates a method in which the. timeelement feature is introduced by means of a mechanicalmovement. The stator arm 5 when in central position, holds the cams 59 and 59' in their lowermost position a inst the action of the springs 60 and 60 n so doing the switches 61 and 61 for the holding magnets 17 and Nare held in open osi tion. This is accomplished by-means o the anti-friction roller 62 carried at the lower end of the stator (3 and which is of sufiicient width to engage both the cams 59 and 59 which are arranged in parallel relation with the armature ofthe holding magnet in position to completeits magnetic circuit, and

the terminals carried by the stator arm Gare brought into engagement with the fixed contacts in their paths of movement, the-roller 62 will be moved off from one of the cams 59 or 59. If the stator arm 6 is moved to the left as viewed in Fig. 18, the cam 59 will be tral position and the brake theePposite holding m g Torque therefore released and the spring will move the cam arm in a downward direction. The dash pot 64 will then retard .the downwardmotion of the arm 65 so that the armature of.

the holding magnet will be brought into engagement with the poles of the holdin ma net 17 at a time coincident with -or slight y before the switch 61 is closed.

Various other modifications could be made by those skilled in the art without departing from the operation and scope of my invention, as defined by the claims.

The various modifications 1n Figs.'13 to 18 inclusive, have been set forth to illustrate some variations that could be made, each modification embodying the principles of closing the magnetic circuit of the holding magnet before or substantially at the same time that its electric circuit is closed. In the event of the load tending to drive the hoisting machine, the tendency would be to rotate the stator to central position and then to the opposite limit of its rotating movement, at some time afterv it had received its initial rotative movement, but-the holding magnet prevents this. holding magnet need not be of large dimensions for the reason that the magnetic circuit is closed at the time it receives current and therefore it does not need to exert its influence through an air gap. On the stopping of the elevator the current is cut 05 from the motor and conse uent-ly at the same time also from the ho ding magnet.

will no longer exist between the rotor and stator, and the, holding efiect of the holding'magnet no longer existing, the stator will toe-returned to 1ts cenby means of a centering device, will be immediately applied.

The 0 eration of the release and a plication of t e brake when'current is app hed to produce movement of the car'in the opposite direction, is similar to that above noted, with the exception that the initial torquebetween the stator and oi the stator arm and the armature against It should be noted that the rotor would effect a rotation The fact that in order to release the brake, cur-rent 1s sent only to the motor,

makes itclear that in star'tmg no current 18.

required other than that necessaryto pro duce the starting torque in the motor, and this may of course be only that required by the most desirable type of motor which may be employed. This same fact makes it clear that it is absolutely impossible to release the brake unless current is already in the motor, and it will be equally clear that by proper adjustment of the amount of torque necessary to work against the centering device, this principle may be still further refined to insure also that the current admitted to the motor must be right in every way to lift or en port the heaviest load on the elevator, be ore the brake will release, thus insurmgthe absolute safety of this device in this most important particular. The fact that the circuit to the holding magnet is completed after the magnetic circuit has been closed mak magnet a very small and almost negligible quantity.

Various centering devices independent of the brake spring and cami9 may be used if desired. For the purposes of illustration, I have shown some types of centering devices in Figs. 7 to 12 inclusive. In Fig. 7, 66 designates an arm movable with the stator frame 1, and 67, 67 designate the centering sprin In Fig. 8. two arms are shown ,mova le with the stator frame 1, said arms being held substantially in horizontal position by the centering springs 67, (37. In Fig. 9 a single centering spring 69 is employed, a flexible device 70 connecting, said spring to a lug 71 on the stator frame 1. In Fig. 10 is illustrated a centering device s1m1- lar to that shown in Fig. 9 in that a weight is substituted for the spring. In Fig. 11 a segment 72 is movable with the stator frame land meshes with the rack bar 7 3 which is actuated upon by the centering springs 67, 67. In F1 12 a bar 74 is pivoted to the journal l 0 the stator frame 1 at 75 and has a .pin-and-slot connection at 7 6 with the rigid support'i? for the centering spring 69.

While the torque release brake herein described, is illustrated in connection with an alternating current elevator, it is ap licable also to direct current, and to any orm of alternatin current or direct current appa: ratus in w ich the action of the brake simultaneously with the application or interruption of desired.

InFig. 2 I have illustrated the application of the. brake to an elevator machine employin the sheave drlve rmciple of what are own as traction e evatorsff l have also shown in Fi 2 a very efiicient type of speed reduction in that herring-bone or double helical gears with cut teeth are es the current taken by this power, or approximately so, is

used. Fig. 3 illustrates a paratus similar hoisting drum E. S designates the switch to Fig. 2 but illustrates rther how the in the car for cont-rolling the reversing brake may be used with elevator apparatus switches Rand R; The holding magnet employing means for increasing the amount connections areillustrated diagrammatically of friction contact with the traction sheave. at 101 at the lower part of the elevator mo- 70 Fig. 6 illustrates in detail a herringbone tor M. The exact connections of the holdgear with cut teeth. ing magnet that may, be used are clearly The introduction of Figs. 2, 3 and 6 illustrated in Figs. 1 8 to 18 inclusive. By

brings out more clearly the safety, importhrowing the controlling switch in the car 10 tance and o erative advantage of the torque to one 0 its circuit-closing positions, the cor- 75 release bra e. The illustration of a more respondin core of the solenoid 85 or 85 on efi'icient type of gearing than the gearing the contro board will be excited with single ordinarily employed with the type of ele'-' phase current. Thereupon either the switch vator shown in Fig. 1, brings more clearly Ror R will be operated so as to close the to the mind the fact that it is quitepossible main line circuit between the main line 80 for the load to start and accelerate to a switch Land the motor terminals 26, 27 and high speed provided the brake is released 28, in the proper direction to start the car with nocurrent in the motor. As hereinupwardly or downwardly as desired. Obbefore explained, the torque release; brake viously any suitable form of reversing switch provides against such contingency. It is may be used, but in this instance circuit- '85 obvious, however, that the more efficient the cl sing plates are attached to the solenoid gearing is, the smaller the. motor. ne d b rods of the 'electro-magnets 85 and 85. and in consequence the smaller will, be the When either the switch R or switch R is starting current necessary both on,-account' closed, not only is the circuit closed to, the.

' of the total work to be accomplished at the motor stator terminals, but 180 to the COII- 90 motor shaft while running as well as on tacts carried by the stator arm 6 as illusaccount of the smaller amount of mass in the trated in 'Fig 1 t0 1 in iv A merotor'itself to be accelerated. The total cost h mical interference bar 102 may be interof current for running the elevator will posed between the solenoid rods to prevent d0 therefore be smaller'and the wear and tear h he Swi h s R an R f m ng 95 on the brake apparatus will be less due to closed at the same time. Small dash pots 86 the smaller, amount of mass to be topped, and 86' may be placed in convenient pOSiand the initial costof the power unit n tion to prevent too sudden reversal of the sary together with any controlling device phase relation of the current to the motor.

h h ay b em loyed in conjunction When the carswitch is brought back to cen- 100 therewith, will be lower. All these advantral position, the controlling electro-inagnet tages may be obtained and the apparatus 85 or 85 which has been operated, will restill rendered safe by the employment of the lease its core and the circuit-closing plates torque release brake/ The torque releasing movable therewith so-that the corresponding 40 brake on the motor shaft may be used in swit h R or R wi l be moved t pen p si- 105 conjunction with a similar brake on the low i n- The power to the motor M is this cut speed shaft of a speed reducing devi e for off and also to the holding magnet, thus alelevators or other purposes, or in c0njunclowing the brake spring or one of the center tion with mechanical or electrical ring devices illustrated in Figs. 7 to 12 inclugency brakes which are used at the terminal sive, to bring the motor stator 1' to central 1 of travel oftheelevator car, or in conjunc- PO itiOH and permit the application of th tion with a dynamic, or air brake. The parbrake apparatus to'stop the motor hoisting ticular point to be noted is the absolute conapparatus and the car. nection between the power application and It will be noticed that circuits have been the brake release, and between the power provided in conjunction with the regular 115 cutofi" and the brake application; together type of automatic limit switches on the elewith the fact that no additional current for I vator machine, to bring the car to rest at its releasing the brake is required at the critical limits of travel and still allow it to be regu moment of starting, and that but a very larly operated in the opposite direction to small amount of current is required during that in which it traveled before operating 1 the running of the (motor to secure the holdone of said limit switches. Additional ing of the brake injoif position. safety devices may be used, as for example, Referring now to Fig. l, the circuits of an automatic means for opening the main line electric elevator system to which my invencircuit, and as disclosed in my co-pending tion may be applied, will be traced so far as application, Serial} No. 324,542, filed July 3, 125 IS deemed necessary to explain the operation 1906, for an improvement in safety release of saidsystem and-the automatic torque 'remagnet for brake apparatus. lease brake. C designates the elevator car, Assumin that it is desired to move the which is connected by means of the cables 7 8 car u war y, the switch lever 90 in the car passing over the sheaves and 79 to the shoul be moved into engagement with the contact, 89, whereupon the single-phase circuit will be closed from the main through the wire 91, solenoid of the magnet 85, and

being thus energized, the switch R'- will be closed against the momentary retarding'action of the dash pot 86 and'the stator frame 1 moved to proper position as hereinafter explained, so as to close the magnetic circuit of the holding magnet before its electrical energizing circuit is closed. 'The stator frame is rotated to bring the armature carried by the stator arm 6 against the holding magnet and substantially at the same time releasing the brake apparatus to permit the rotor to rotate and also closing the circuit to the holding magnet so that the stator frame will be held in its limiting position and consequently the brake apparatus held in re-.

leased position.

' Although I have herein shown certain apparatus to illustrate the principles of my invention, it is obvious that those skilled in the art may make various changes in the de tails and the arrangement'of parts without departing from the spirit and scope of my invention as defined by the claims. I desire therefore not to be limited to the exact construction herein disclosed.

Having thus described my invention, what I desire to have protected by Letters Patent of the United States is 1. The combination with an alternating current motor, brake apparatus therefor, electric means for holding said brake apparatus in released position, and means for closing the magnetic circuit of said holding means at the same time. or before its electrical circuit is closed.

2. The combination with an alternating current motor having a movable stator frame, of brake apparatus'for said motor,

connections between the stator frame and said brake apparatus to efiect a release of the latter upon the stator receiving current, an electro-magnet for holding said stator frame in brake-released position, an armature moved bysaid stator frame, and an electric switch for said holding magnet. and controlled by the stator frame to efiect its closure substantially at the same time or after the armature has "been moved'into engagement with the poles of the magnet.

3'. The combination with a motor, of a brake. therefor, brake-applying mechanism, a holding electro-magnet, and means for simultaneously completing the magnetic and a 8-1:; the circuit tion with a revoluble stator frame,

electric circuits of said holding electro-magnetand' acting upon said brake-applying mechanism to effect a release of the brake. 4. The ,combination with a motor, brake apparatus therefor, an electro-magnet for holding the brake in released position, and means for energizing saidelectro-magnet simultaneously with or after the closure of its magnetic circuit.

5.'ThG'COI1'lblIl-fltl0ll' with a motor, of a brake therefor, means co-acting with a part of the motor for releasing said brake, a holdin device for maintaining the brake in released positiomand means for rendering effective said holding device after the brake has been released.

.6. The combination with a motor, of a brake therefor, brakeapplying apparatus, brake-releasing mechanism, an electro-magnet for holding said brake in released position, and means for simultaneously or successively completing the-magnetic and electriccircuits of said holding ele'ctro-magnet and operating said brake-releasing mechanism to release the brake.

7. In a torque-release brake, the combina tion with a stator frame of an alternating current motor, of a brake for the rotor, means actuated by movement of the stator frame for releasing said brake, an electromagnet for holding saidstator frame in its limiting position and the brake in released position, gization ously with or after the closure of its mag netic circuit.

8. In a torque-release brake, the combination with a revoluble stator frame of an aland means for effecting the enerternating current motor, of a brakev for the rotor, brake-releasing apparatus actuated by the stator frame upon movement thereof, an electro-magnet, an electric switch for said electro-magnet, and means carried by the stator frame for closing the ma etic circuit and the electric circuit of said electromagnet to cause the latter to hold the stator frame in its limiting position.

of said electro-magnetsimultane- 9. In a torque-release brake, the combination with a revoluble stator -frame, of a brake for the'rotor, brake-releasing mechanism, a cam for actuating said mechanism upon movement of said frame in either direction from a predetermined position, two

electro-magnets for holding said stator frame in its limiting positions, an armature connected to said frameiand moved therebyv against the poles of either of said electroma nets, and an electric switch for each of sai electro-magne frame to effect the energization of the cor responding magnetic circuit.

10. In a torque-release brake, the comb1naof electrotsand o ,erated b said holding electro-magnet simu l-' 'taneously with 'or after the closure of its magnets for limiting. the movement thereof the brake when and holding the-same in limiting position, a switch for each electro-magnet and operated'loy said frameto effect the energization of the corres ondin electro-magnet simultaneousl with or a er its, magnetic circuit is comp eted, a brake for the rotor, brakereleasing apparatus operated by saidframe upon application of current to the motor,

and means for returning the stator frame to' normal position to efi'ect the ep'lica'tion of the current to t e motor is out off.

11. In an elevator system, the combination with a car, hoisting apparatus and motor, oi a brake for the rotatlve part ofsaid motor,

nets simultaneously with or brake releasing apparatus operated by a limited rotative movement of the other part of the motor, electro-magnets for holding the said other part in limiting osition an the brake released, and means current "to one of said holding electro-magafter its magnetic circuit is completed. I

In testimony whereof, I have signed my name to this specification in the presence of twosubscrihing witnesses.

WILLIAM N.- nroKrNsoN, JR. Witnesses: v

W. H. STOKES CHARLES M. hirssnn.

or directing 

